Problem: Is ${155404}$ divisible by $4$ ?
Explanation: A number is divisible by $4$ if the last two digits are divisible by $4$ . [ Why? We can rewrite the number as a multiple of $100$ plus the last two digits: $ \gray{1554} {04} = \gray{1554} \gray{00} + {04} $ Because $155400$ is a multiple of $100$ , it is also a multiple of $4$ So as long as the value of the last two digits, ${4}$ , is divisible by $4$ , the original number must also be divisible by $4$ Is the value of the last two digits, $4$ , divisible by $4$ Yes, ${4 \div 4 = 1}$, so $155404$ must also be divisible by $4$.